DE102009046406A1 - peristaltic pump - Google Patents

Abstract

The invention relates to a peristaltic pump for use in medical technology with a stator 40 and a rotor 20, wherein the stator 40 has a roll bed 12 which corresponds to the contact area to a recorded tube 30 and the rotor 20 rolling elements 24 are provided which are suitable are to close a recorded between the trolley 12 and the rolling elements 24 hose. In this case, the roll-bed 12 at least partially has an electrically conductive surface for reducing and / or avoiding electrostatic charging of the hose 30.

Description

The invention relates to a peristaltic pump according to the preamble of claim 1.

In the medical field, peristaltic pumps are used to deliver extra-corporeal fluids or to provide them precisely to volume. An application for peristaltic pumps can be found in dialysis machines, in which dialysate of the dialysate, dialysis and / or blood must be pumped. In a peristaltic pump, a flexible tube is placed along a cylindrical inner diameter and locally closed or occluded by radially outwardly acting pressure rollers and by the movement of the driven rollers along the tube is closed place shifted and so realized the fluid delivery. An advantage of peristaltic pumps lies in the relatively good metering. Since only the tube with the pumped fluid comes into contact, a peristaltic pump can be quickly and inexpensively cleaned by replacing the hose.

Due to the contact of the rollers to the hose, associated with walking and friction, triboelectric charging may occur on the hose. Above all plastic surfaces are prone to such charges. In this case, charges are built up and exchanged by the contact and friction of the surfaces of the stator, the rotor, so its driven rollers with the hose and when removing the rollers from the hose they can not be compensated quickly enough and remain as electrostatic charges on the respective surfaces. The charges are created by first pressing the hose by the pressing force of the rollers, both on the trolley, as the corresponding contact surface of the stator, and the rollers. As the roller continues to roll, the respective roller lifts off the tube section, so that the described electrostatic charging of both the tube and the roller bed and the rollers may occur. Furthermore, the rollers in the area of execution of the hose from the hose pump completely lift off from the hose. As the rotor continues to rotate and the respective reel comes into contact with the hose in the area where the hose is being inserted, electrostatic charges accumulated on the reel may be transmitted to the hose causing a corresponding glitch. These charges lead to an electrostatic charge of the hose and in particular its outer surface. The charge separation is in fact effected according to the triboelectric effect in that different materials have different electron affinity and in the separation of corresponding materials, the electrons can not move freely enough so as to effect a charge balance.

In addition to the generation of the charges in contact from the roll to the hose, there may also be corresponding electrostatic charge formations between the hose and the roll-bed. If, in fact, when the rotor continues to travel, the respective roller lifts off from the corresponding hose section, the elastic restoring forces within the hose cause it to return to its round basic shape, so that the hose is no longer in surface contact, but only in line contact with its trolley. This is a partial lifting of the hose from the hose bed, which can cause electrostatic charges accordingly.

In the medical field, diagnostic devices with high-impedance measuring inputs, such. As ECG devices, used and their measurement results can be disturbed or falsified by the electrostatic charging of the tube. This known problem is mitigated by the recommendation of the competent federal authority BFARM a common equipotential bonding of the devices, so the pump and the diagnostic device, but without being eliminated. These electrostatic charges occur, as already described, as an electrical interference pulse, in particular when placing the rollers on the hose on. Dry ambient air can amplify this problem. As insufficient approaches to the elimination of such charges anti-static sprays are known. Also suitable for reasons of biocompatibility hoses made of special, z. B. metal-containing materials not to reduce the charges.

Although some ECG devices can filter out these disturbances, and in particular the glitches, by using appropriate filters, but in special applications such. As in the review of cardiac pacemaker signals such filters can not be used, since the measured pacemaker signals are very similar to the interference signals. It can, as under US 3,580,893 , an electrical grounding cable is attached directly to a hose to prevent charging. Furthermore, are off WO 2004/109206 A1 Hose connector with galvanic contacts known for grounding. Or it can ground connector - as under WO 2009 / 044220A1 disclosed - attached to the appropriate hoses. This prior art has the disadvantage that it is directed less on the emergence, but more on the transmission and harmful effect of the charges. In the US 5,127,907 In this case, the approach is chosen that parts which are in a relative movement to each other, are made of similar materials. The disadvantage is found in the known solutions also the additional upgrade effort and the additional costs.

Object of the present invention is to avoid disturbing influences of electrostatic charges or electrical impulses from a peristaltic pump to electronic devices or at least reduce.

This object is achieved by the features of claim 1. Preferred embodiments will become apparent from the dependent claims.

According to the invention, a peristaltic pump is provided for use in medical technology, with a stature and a rotor, wherein the stature has a trolley, which corresponds to the contact area to a recorded tube and rolling elements are provided on the rotor, which are suitable between the trolley and To close the rolling elements recorded hose. In this case, the trolley has at least partially an electrically conductive surface for reducing and / or avoiding electrostatic charging of the hose. The rolling elements may be rollers or balls and the trolley may also have several separate areas of the conductive surface. In the area which has been overrun by a rolling element, the hose due to internal restoring forces tends to revert back to its original cylindrical shape, and with this deformation portions of the hose are lifted off the trolley and it has been recognized that, due to a lack of charge exchange in This separation area can cause electrostatic charges on the tube surface. A metallic surface of the rolling bed supports the exchange of charge and prevents or at least reduces the formation of corresponding electrostatic charges.

This embodiment eliminates the need for additional user-visible devices on the peristaltic pump and / or tubing system to prevent electrostatic charging. The operator does not have to carry out any additional upgrade steps and has an unchanged visual impression of the peristaltic pump and the medical device in which the peristaltic pump can be integrated.

In addition, an equipotential bonding, in particular in the form of a grounding, can be provided on the electrically conductive surface. This equipotential bonding can be done by sensitive electronic devices, which are in the vicinity of the peristaltic pump and could be disturbed, z. B. by an electrical conductor, to the same electrical potential as the hose pump and in particular its trundle bed are brought. Also, a potential equalization can be created by grounding in the electrical supply network, which allows a free charge balance and thus prevents charging of the hose surface or at least effectively reduced. A preferably provided between the equipotential bonding and the electrically conductive surface electrical resistance limits the leakage current and thus prevents a transmission of interference signals by means of grounding to other devices connected there.

Furthermore, the rolling elements preferably also have an electrically conductive surface, which is the lateral surface in the case of cylindrical rollers, and there is an electrically conductive contact with the electrically conductive surface of the rolling bed of these surfaces. In this way, the same electrical potential lies on both sides of the hose between the respective rolling element and the rolling bed, so that the formation of electrostatic charges on the hose is further reduced as a result.

In a further embodiment of the invention, the complete trolley has a continuous electrically conductive surface. In principle, the trolley bed can have only partially, ie in particular sections, a conductive surface, but a corresponding continuous conductive surface improves the charge balance. It is advantageous, in particular, that this already prevents (or at least reduces) the formation of electrostatic charges, which is significantly more effective than dissipating or compensating any charges that may have occurred. This also ensures that no heels and / or unevenness of the rolling bed arise, which can worsen the rolling of the rolling elements and thus the pumping action and can adversely affect the life of the hose.

Constructively, the peristaltic pump can be designed as a hose roller pump, d. H. the trundle bed has a cylindrical inwardly directed surface and the rolling elements are designed as rollers. Hose roller pumps are inexpensive to manufacture and have good properties accurate metering. Alternatively, the peristaltic pump may also have spherical pressure or rolling elements, as will be described in more detail in a subsequent embodiment variant.

Further, the cylindrical surface of the rolling bed may have clearances at one or two locations to serve as a conduit for the hose from the peristaltic pump. This enables a kink-free hose guide.

In a further embodiment, the stator is produced as an injection-molded part and the said electrically conductive surface is the surface of an overmolded metal insert part or an overmolded metal foil. The encapsulation of a metal part allows a good mechanical connection of the metal with the plastic. Since the plastic of the injection-molded part is made of an electrically non-conductive plastic, the charges that may occur on the trolley, are not transmitted through the plastic to other areas of the pump and / or a corresponding medical device. In this case, the plastic material of the stator is electrically non-conductive, so that the charges can not spread over the stator.

Also, further developing the insert part may have a cylindrical basic shape with a flange, which is preferably aligned completely circumferentially and radially inwardly. This geometry corresponds approximately to a kind of box with a bottom, which gives the basic cylindrical shape deformation stiffness. In this case, an opening is advantageously provided concentrically in the bottom, through which the drive axle of the rotor can be guided. Alternatively, the flange may also be directed outwards, i. H. when the insert is overmolded, this flange points in the direction of the plastic and provides a good metal-plastic connection.

In an alternative embodiment, the designated electrically conductive surface of the rolling bed can also be achieved by a conductive coating of a previously produced injection-molded part. The trundle bed should have a high roundness, which is also easy to achieve with modern injection molding machines. A coating of an injection-molded part thus produced, such as a galvanic coating or a pasting, maintains the surface accuracy and in particular the roundness. Also, an electrically conductive metal part, such as. As a stainless steel sheet can be inserted into a correspondingly molded recording of the peristaltic pump, which is a simple and compared to an encapsulation cost-effective manufacturing process and by the pressure forces of the rolling elements, this metal part will nestle well on the injection-molded cylindrical surface of the rolling bed.

Furthermore, a medical device may include a corresponding peristaltic pump, wherein the device has a user-facing operating and functional front, which is formed as an injection molded part, while the peristaltic pump is integrally integrated with the rollaway bed in the control and function front. This creates a holistic front of the device and accordingly an attractive overall design.

Reference to the drawing, the invention is explained in detail below. Show it:

1 a schematic diagram of a hose roller pump,

2 a plan view of a corresponding hose roller pump,

3 a variant of an insert part and

4 another variant of the insert.

1 shows the principle of a hose roller pump. Here is a hose 30 in a cylindrical receptacle of an insert 10 is used and stands circumferentially at about 270 ° in contact with the inside of the insert. This area will subsequently also be used as a trundle bed 12 designated. Coaxial to the insert 10 is a rotor 20 arranged with two drive arms, to each of which a rolling element 24a . 24b is rotatably mounted in the form of a cylindrical roller. The rotor is according to the drive direction 22 driven by a motor (not shown). The upper rolling element pushes 24b so radially outward against the hose 30 in that it closes itself locally. Now, when the drive moves the rotor, this closed position moves clockwise. Here comes the lower rolling element 24a in engagement with the tube and closes it accordingly and so the volume of fluid between the two closed points is conveyed in the longitudinal direction of the tube. The hose is stationary to the insert part 10 and its trundle bed 12 and it finds a rolling motion between the rolling elements 24a . 24b and the hose instead. The outer rolling radius 26 The rolling elements is dimensioned so that it is essentially around twice the wall thickness of the hose 30 smaller than the inner radius of the insert 10 is so as to close the hose sufficiently well without squeezing it too much.

To realize a desired radial pressure force from the rolling elements 24a . 24b against the hose 30 can, as in 2 represented, also each a compression spring 28 be provided, which is located on the rotor 20 supported and via a roller arm 29 the roles 24a . 24b accordingly pushes outwards. Each of the two roller arm 29 is on the rotor 20 pivotally mounted, has a pressure surface for the compression spring 28 and also a storage for one of the rolls 24a . 24b on. It can also be used a higher number of rolling elements.

The insert part 10 is as a kind of can made of a metallic material such. B. stainless steel bleach executed. That is, it has a cylindrical basic shape and becomes an axial side of a flange 14 limited, which extends radially inward and a coaxial opening 16 for the drive axis of the rotor 20 leaves free. The cylindrical face of the flange 14 is in 1 and 3 with the inner diameter of the Flanschabschlusses 15 shown. By a franking 18 , which on the cylindrical basic shape of the insert 10 is provided from the flange is, according to 1 the hose into the interior of the insert part 10 directed. Since the franking has a good 90 ° of the circumference, the roll length of the rolling bed is just under 270 °. For the conveying function of the peristaltic pump, at least one rolling element must always close the hose and so a rolling length of 180 ° would be sufficient for two rolling elements.

Alternative to the version in 3 can the flange 14 also point radially outward or it may be in addition to the in 3 illustrated flange 14 a further outwardly directed flange may be provided at the other end of the insert part.

In the introduction, the technical effect was described that in conventional peristaltic pumps in the rolling of the rollers against the hose, the lifting of the hose from his trundle bed and v. a. Even when placing the respective role on the tube in the lead-in area in the peristaltic pump triboelectric charges and glitches are generated. These are generated in particular in the contact of plastic surfaces to each other.

In the present case is the insert part 10 made of a metallic material and so has the rolling bed, so the cylindrical inner surface of the insert, an electrically conductive surface. As a result, the effect of charge separation and the corresponding charge is greatly reduced or avoided, since the formation of a local excess charge or charge deficiency is prevented by the free exchange of charge on the conductive surface. Furthermore, the rolling elements can also have an electrically conductive surface and, as a result, corresponding charges are also reduced and / or avoided at the hose rolling element contact.

Also, an electrically conductive connection from the rotor 20 with its roles 24a . 24b be provided to the trolley, such as by a sliding contact on the drive axis of the rotor 20 , which is electrically conductive with the insert part 10 is connected (not shown) and so this effect of avoiding the charges is reinforced.

In the embodiment described here, the entire trolley is made electrically conductive. But there is already a significant reduction in glitches when the trundle bed only in the input and execution area of the hose 30 is provided with conductive and grounded sections. Charges that are on the outside of the hose or corresponding interference pulses can be dissipated through the ground.

The insert part 10 can be inexpensively manufactured in a deep-drawing process with a precise roundness and with a smooth surface of a metal sheet. This insert is used in an injection molding tool. In the injection mold, the insert is molded and forms a positive and firm connection with the overmolded body of the peristaltic pump. Also, the peristaltic pump may be integrated into the front panel of the corresponding medical device to be easily accessible to the operator. In this case, the insert is molded in the corresponding front panel.

Alternatively, the insert can also be a metal foil, which can be inserted annularly into the injection molding tool and molded around.

Alternatively, the metallic surface of the rolling bed can also be subsequently applied to a molded plastic molding. For such conductive coatings MID (Molded Interconnection Device) technology can be used. Although this technology is primarily used for the production of three-dimensional traces for electrical circuits, it is also possible in this way to produce continuous conductive surfaces. In this case, a suitably coatable plastic is used, which is galvanically provided with a corresponding metal layer. If in a two-component injection molding process this coatable plastic is used exclusively in the area of the rolling bed, then another material can be used for the front of the device. Also, a stainless steel foil or stainless steel sheet can be clamped in the cylindrical receptacle and / or glued.

The insert part 10 (please refer 3 ) has a franking 18 on which according to 1 both for insertion and removal of the hose is used, so that the rolling length, so the pressure surface of the hose in the trundle bed, 270 °. Alternatively, an insert according to 4 used, which at two opposite places two smaller frankings 18 having. This insert can be used in a peristaltic pump in which the tube is introduced on a first side in the cylindrical portion, out there over one and a half rounds and leaves the pump on a second opposite side. Also, the hose can be guided with more revolutions in the pump.

4 schematically shows a resistor R, which electrically between the insert part 10 and a potential equalization or in particular a ground is connected. This equipotential bonding can also be done with the rotor 20 be connected. The resistor R causes a limitation of the leakage current of the interference signal. If a sensitive device is connected to the equipotential bonding or grounding, this prevents interference signals from being passed on to this device via equipotential bonding.

So far, a hose roller pump has been described in the exemplary embodiment, which uses rollers as rolling or pressure elements. The invention is accordingly applicable to peristaltic pumps with spherical rolling elements. Such a peristaltic pump is similar to a radial ball bearing, wherein the outer race of the stator is, which has circumferentially a concave recess in which the hose is located, which is successively closed locally by preferably two outwardly pressing balls. The drive of the pump takes place directly on the balls, which are comparable to a radial ball bearing guided in a cage.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 3580893 [0006]
• WO 2004/109206 A1 [0006]
• WO 2009/044220 A1 [0006]
• US 5127907 [0006]

Claims (12)

Peristaltic pump ( 1 ) for use in medical technology with a stator ( 40 ) and a rotor ( 20 ), wherein the stator ( 40 ) a trundle bed ( 12 ), which is the contact area to a recorded tube ( 30 ) and on the rotor ( 20 ) are rolling elements ( 24 ), which are suitable to move one between the trundle bed ( 12 ) and the rolling elements ( 24 ) closed hose, characterized in that the trolley ( 12 ) at least partially an electrically conductive surface for reducing and / or avoiding electrostatic charges of the hose ( 30 ) having. Peristaltic pump according to claim 1, characterized in that the electrically conductive surface ( 12 ) has a potential equalization, in particular in the form of a ground. Peristaltic pump according to claim 2, characterized in that between the equipotential bonding and the electrically conductive surface ( 12 ) An electrical resistance (R) is provided. Hose pump according to one of the preceding claims, characterized in that the rolling elements ( 24 ) have an electrically conductive surface and that of these surfaces an electrically conductive contact to the electrically conductive surface of the rolling bed ( 12 ) consists. Peristaltic pump according to one of the preceding claims, characterized in that the complete trolley ( 12 ) has a continuous electrically conductive surface. Peristaltic pump according to one of the preceding claims, characterized in that the trolley ( 12 ) has a cylindrically inwardly directed surface and the rolling elements ( 24 ) are executed as rollers. Peristaltic pump ( 1 ) according to one of the preceding claims, characterized in that the contour of the rolling bed at one or two places franking ( 18 ) to serve as an input or design for the hose from the peristaltic pump. Peristaltic pump according to one of the preceding claims, characterized in that the stator ( 40 ) was produced from an electrically non-conductive plastic in an injection molding process and the electrically conductive surface, the surface of an overmolded metallic insert part ( 10 ) or an overmolded metal foil. Peristaltic pump according to claim 8, characterized in that the insert part ( 10 ) a cylindrical basic shape with a flange ( 14 ), which is preferably aligned completely circumferentially and radially inwardly. Hose pump according to one of claims 1 to 7, characterized in that the electrically conductive surface has been produced by a local conductive coating of an injection molded part. Medical device for extracorporeal blood treatment, in particular for dialysis and / or an infusion or transfusion device, with a peristaltic pump ( 1 ) according to any one of the preceding claims. Medical device according to claim 11, wherein the device has a user-facing control and function front, which is formed as an injection molded part and wherein the peristaltic pump is integrally integrated with the roll-away bed in the control and function front.

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